Natamycin (also known as pimaricin or tenecetin) is a member of the polyene family of antimycotics (Florey, "Analytical Profiles of Drug Substances", Vol. 10, 1981; Merck Index, 8th ed., "Pimaricin", p. 834). Natamycin has been produced in purified form and, in this form, is known to be an effective antifungal agent. Carter, U.S. Pat. Nos. 4,536,494 and 4,600,706, discloses that dry, crystalline natamycin physically mixed with feed grain in effective amounts, prevents fungal mycotoxin contamination of feed. Elliott, Canadian Patent 684,259, discloses feed additives of Candida albicans fermentation product, with or without the inclusion of an antifungal agent such as nystatin or pimaricin.
Natamycin is prepared by fermentation, such as disclosed in U.K. Patent 846,933, using Streptomyces gilvosporeus. In this process, natamycin is recovered by methanol extraction followed by tedious steps of adsorption and elution. Bridge, U.S. Pat No. 3,378,441, discloses recovery of natamycin by salting it out of the fermentation broth, extracting with methanol, removing the solids, and then evaporating the liquid. Struyk, U.S. Pat. No. 3,892,850, discloses recovery of natamycin by extraction with acidified butanol followed by distillation and precipitation. Each of these processes require an expensive recovery step, such as adsorption and elution, distillation, or evaporation. Consequently, natamycin has not been widely used because of its extremely high cost of manufacture, isolation, and purification. A need exists for a method of using natamycin that does not require an expensive recovery step.